Precipitation apparatus



P 1929- R. w. SHAFOR ET AL 7 1,708,332

PREC IPI TATION APPARATUS Filed July 19, 1924 3 Sheets-Sheet 1 A TTORNEY;

April 9, 1929- R. w. SHAFOR ET AL 1,708,332

PRECIPITATION APPARATUS Filed July 19, 1924 3 Sheets-Sheet 2 April 9, 1929.

R. w. sHAFdR ET AL PRECIPITATION APPARATUS Filed July 19, 1924 3 Sheets-Sheet B. A B. Nees BY Bron n ATTORNEY. v

Patente'd Apr. 9, 1929. i

PATENT OFFICE.

RALPH W. SHAFOR, ALPHEUE R. NEES, AND ROBERT J'. BROWN, OF DENVER, COLO- RADO.

PRECIPITATION APPARATUS.

Application filed July 19, 1924. Serial N0. 727,089.

Our invention relates to apparatus for precipitating precipitable substances from their solutions and its principal object is to accomplish in a continuous operation the formation of a precipitate in large sized particles by the application of heat to the material in a diluted condition.

The invention is particularly adapted to carry into practice a process of precipitating hot saccharates from cold waste waters obtained by the Steffens process of recovering sugar from molasses in the beet-sugar industry as fully described in our copending application for patent Serial No. 727,088, filed July 19, 1924, and in the following description the construction and operation of the apparatus in which the invention is embodied, will be more clearly brought out by reference to the above stated process which briefly is as follows.

The process is based upon tne principle that by diluting a solution such as the cold waste water obtained in the before mentioned Steffens method of recovering sugar from molasses, with a larger volume of barren mother liquor, the consequently reduced concentration of the sucrose and lime in the solution will cause the formation of larger crystals upon their precipitation by means of heat. I

The rate of sedimentation of the precipitate is proportionately increased and the separation of the precipitate from the mother liquor is in consequence expedited and facilitated.

The term dilute is used in this description in the sense of mixing a solution of solids with a liquid defined inpage 171, Principles of Physical Chemistry, by Washlnirn, whereby the concentration of solids in the solution is reduced.

lVith the above objects in view, the process consists in producing in a suitably constructed container a circulatory movement of a volume of barren mother liquor substantially free from precipitable matter, although it may contain precipitated matter, and into thiscirculating curent is introduced a comparatively small stream of pregnant cold waste water. The thorough intermixture of the two'liquids is efiected by a propeller which also serves to produce the circulating current, and an overflowof surplus mother liquid carrying the precipitate in suspension compensates for a continuous feed of fresh material.

I The precipitation of the sucrose and lime in the diluted material, either separately or combined, is produced in a zone separate from the mixing zone by heat preferably supplied through the medium of steam. V

In the acompanying drawings, in the several views of which like partsare similarly designated,

Figure 1 represents a plan View of the apparatus embodying the features of our invention;

Figure 2, a vertical section taken on the line 22, Figure l; and

Figure 3, a horizontal section along the line 33, Figure 1.

Referrin more specifically to the drawings, 5 designates a tank preferably of cylindrical form, haying in its bottom portion an inwardly sloping concrete fillet 7.

The top of the tank is closed by a reenforced cover 8 provided with a vent hole 9, and supported within the tank in coaxial relation to its circumferential wall is a funnel 12, the open ends of which are spaced from the cover and from the bottom of the tank.

A screw propeller 18 in the lower end portion of the funnel is mounted upon a vertical shaft 1% supported for rotation in a step bearing upon the bottom of the tank.

The shaft extends through a thrust bearing 16 which is mounted upon channel bars 1'? supported on the cover 8, and it is by incans ofbcvel gears 19 and 20 connected vith a line shaft 18 which carries a pulley 21 for its connection with a conveniently located motor.

The annular space 22 in the tank exteriorly of the funnel constitutes the precipitation zone of the apparatus in which the precipitate is formed by the introduction of steam through perforated coils 23 and 24 which are disposed concentrically in the lower portion of the precipitation zone in connection with supply pipes 23 and 24 extending through openings in the cover.

The material is fed into the mixing zone of the funnel immediately above the propeller, through a plurality of pipes 25 likewise extending through openings of the cover for connection with a supply manifold 26 and the flow through each pipe is controlled by a manually adjustable angle valve 27. I

lnthe operation of the apparatus, the propeller produces a circulating current of a liquid with which the tank is filled to a leveldetormincd by an overflow-opening 28 in the circumferential wall of the tank, the current passing upwardly through the precipitation zone and downwardly through the funnel andaround the vends thereof, and in order to prevent the liquid in the current swirling horizontally, both the interior of the funnel and the precipitation zone exteriorly of the; same, are divided by radial partitions andf30. 1L! drain'opening 31 in the bottom of the tank provides for the d scharge liquid and settled matter when the apparatus is not in operation, I

In the performance of the process of. precipitating the sucrose and lime constituents of the cold waste Water, the tank is filled with barren mot-her liquor to the level determined bythe point of overflow. This is preferably accomplished by. first filling the tank with pregnant cold waste and then forming the .hot saccharate precipitate? of the sucrose and lime contained therein by a circulatory movement of the liquor induced by the movement of the propeller, and by the introduction of a heating fluid through the perforated coils to a temperature of from to C.

After the precipitate been fo med an d the mother liquor is substantially barren of precipitalle matter, fresh cold waste is delivered into; the mixing zone through the pipes 25. The feed is immediately intermixed with the current of barren liquor passing downwardly through the funnel and thereby diluted to many times its volume and whileit jpasses upwardly through the precipitation zone, its sucrose and lime whose concentrations were reduced in proportion to.

the dilution are precipitated by the heat constantly supplied by the steam entering from theperforated coils 23sec. 94-. i

It will be evident that in order to obtain the most satisfactory results no precipitate should be formed before the feed is diluted and since the current of barren liquor passthrough the funnel is of comparatively high temperature, it obviously essential that the dilution of the cold waste take place immediately uponits enteringrthe tank.

It is for this reason advisable that the feed pipes have their-outlets in as close proximity tothe propeller as is permissible for the int'ermixture of the inflowingwastc water with the circulating current of barren liquid.

i In order to produce the required dilution of the waste water, the propeller isoperated to produce a current velocity; many times that of the feed-stream, it having been found to .a precipitating hea th at approximately 4L0 cubic feet of'current against 2 cubic feet of feed per unit of time have produced a desirablereduction in the concentration of precipitable substances (from 1% by weight in the cold waste to .05 in the ii'iiXt'ure). r

It is essential that the velocity of the current in the precipitation zone be regulated in ratio to its volume to allow for precipitation to proceed practically to completion before the current reaches the level determined by the overflow, so that the liquor entering the funnel at the upper end thereof be substantially barren ofprecipitable Ina-tter for dilution v of the inflowing cold ce'crease the streams ofinfiowing cold waste according to the current velocity, tempera ture and othervariable conditions in the tank and it will be understood that this is easily done by equipping the apparatus with the maximum number of pipes and then reglz l g their operation by Ineansof the valves 27. i f

, Having thus described our inventionqvhat we claim and desire to secure by Letters Patent is: c i

1. Apparatus for the precipitationof precipitable substances from their solutions comprising in combination, a vessel adapted to contain'a diluent bath and having'an overflow to i'naintain' a determinate volume of sai d bath by the discharge of surplus liquid, the vessel being divided into a mixing zone and a precipitation zone communieating in the lower portion, of thesame,

comprising in combination, a vessel adapted tov contain a diluent bath and having an overflow to maintain a determinate volume of said bath by the discharge of surplus liquid,-the vessel being divided into a mixingzone and a precipitation zone communicating in the lower portion of the same, av propeller in the mixing zone adapted to produce. a current. circulating from the'miX- ing zone downwardly into the'precipitation zone, means to feed solution into the bath in the mixing zone, in close proximity to the propeller, and means to subject-the bath. in the lower portion of the precipitation zone SVApparatus for the precipitation of precipitablesubstances from their solutions comprising in combination, a vessel adapted to contain a diluent bath and having an overflow to maintain a determinate volume of said bath by the discharge of surplus liquid, the vessel. being divided into a mixing zone and a precipitation zone communicating in the lower portion of the same, means in the mixing zone adapted to pro duce a current circulating from the mixing zone downwardly into the precipitation zone, distributive means to feed solution into the bath in the mixing zone, and means to subject the bath in the lower portion of the precipitation zone to a precipitating heat.

at. Apparatus for the precipitation oi precipitable substances from their solutions comprising in combination, a vessel adapted to contain a diluent bath and having an overflow to maintain a determinate volume of said bath by the discharge of surplus liquid, the vessel being divided into a mixing zone and a precipitation zone communicating in the lower portion of the same, means in the mixing zone adapted to produce a current circulating from the mixing zone downwardly into the precipitation zone, means to feed solution into the bath in the mixing zone, means to oppose lateral deflection of the current in the bath, and means to subject the bath in the lower portion of the precipitation zone to a precipitating heat.

5; Apparatus for the precipitation of precipitable substances from their solutions comprising in combination, a vessel adapted to contain a diluent bath and having an overflow to. maintain a determinate volume of said bath by the discharge of surplus liquid, the vesselbeing divided into a mixing zone and a precipitation zone communicating in the lower portion of the same, a prope lcr in the mixing zone adapted to produce a current circulating from the mixing zone downwardly into the precipitation zone, a plurality of conduits connected to distribute a solution in the bath in the mixing zone immediately above the propeller, and means to subject the bath in the lower portion of the precipitation zone to a precipitating heat.

6. Apparatus for the precipitation of precipitable substances from their solutions comprising in combination, a vessel adapted to contain a diluent bath and having an overflow to maintain a determinate volume of said bath by the discharge of surplus liquid, the vessel being divided into a mixing zone and a precipitation zone communieating in the lower portion of the same, radial partitions in the zones to oppose lateral deflection of the current, means in-the mixing zone adapted to produce a current circulating from the mixing zone downwardly into the precipitation zone, means to feed solution into the bath in the mixing zone, and means to subject the bath in the lower portion of the precipitation zone to a precipitating heat.

7. Apparatus for the precipitation of precipitable substances from their solutions,

comprising in combination a vessel, means to produce a current of liquid in the vessel in a circulatory movement, a feed adapted to enter material into the current of liquid, and means for heating the current.

8. Apparatus for the precipitation of precipitable substances from their solutions, comprising in combination a vessel, means to produce a current of liquid in the vessel in a circulatory movement, a feed adapted to enter material into the current of liquid, at a plurality of points, and means for heating the current.

9. Apparatus for the precipitation of precipitable substances from their solutions, comprising in combination a vessel, means to produce a current of liquid in the vessel, past a determinate point of feed, a feed adapted to enter material into the current at said point, and means for heating the current.

In testimony whereof we have aflixed our signatures.

RALPH W. SHAFOR. ALPHEUS R. NEES. ROBERT J. BRONN. 

